This article mainly introduces the definition and use of magic methods in PHP. Magic methods are unique features of object-oriented PHP. They are triggered under specific circumstances and all start with a double underscore. You can understand them. For hooks, friends in need can refer to

Magic method is a unique feature of PHP object-oriented. They are triggered under specific circumstances and all start with a double underscore. You can understand them as hooks. Using pattern methods, you can easily implement overloading in PHP object-oriented (Overloading means dynamically creating class attributes and methods). Many magic methods appear in pairs. The following lists all the current pattern methods in PHP.

1.__construct, __destruct

__constuct is called when constructing the object;
__destruct is called when the object is explicitly destroyed or the script ends;

2.__get, __set

__set is called when assigning a value to an inaccessible or non-existent attribute
__get is called when reading an inaccessible or non-existent attribute

3.__isset, __unset

__isset is called when isset() or empty() is called on an inaccessible or non-existent property
__unset is called on an inaccessible or non-existent property It is called when the attribute is unset

4.__call, __callStatic

#__call is called when it calls an inaccessible or non-existent method
__callStatic is called when it is inaccessible or does not exist The existing static methods are called

5.__sleep, __wakeup

__sleep is called when using serialize, which is very convenient when you don’t need to save all the data of a large object. Useful
__wakeup is called when using unserialize and can be used to initialize objects

6.__clone

It is called when cloning an object and is used to Adjust object cloning behavior

7.__toString

Invoked when a class is converted to a string

8.__invoke

Called when the object is called functionally

9.__set_state

This static method is called when var_export() is called to export the class is called. Use the return value of __set_state as the return value of var_export.

10.__debuginfo

Called when var_dump() is called to print an object (when you don’t want to print all attributes) Applicable to PHP5.6 version

PHP magic method usage examples are as follows:

<?php
 
class Magic
{
  public $var = &#39;test&#39;;
 
  //構造函數,在創(chuàng)建對象的時候調用
  public function __construct()
  {
    echo &#39;__construct called&#39;.PHP_EOL;
  }
 
  //某個對象的引用都被刪除、對象被銷毀、調用exit()后、腳本關閉時被調用
  public function __destruct()
  {
    echo &#39;__destruct called&#39;.PHP_EOL;
  }
 
  //當給不可訪問或不存在屬性賦值時被調用
  public function __set($name, $value)
  {
    echo $name.&#39;-&#39;.$value;
    echo &#39;__set called&#39;.PHP_EOL;
  }
 
  //讀取不可訪問或不存在屬性時被調用
  public function __get($name)
  {
    echo $name;
    echo &#39;__get called&#39;.PHP_EOL;
  }
 
  //調用不可訪問或不存在的方法時被調用
  public function __call($name, $arguments)
  {
    echo $name . &#39;-&#39; . implode(&#39;,&#39;, $arguments);
    echo &#39;__call called&#39;.PHP_EOL;
  }
 
  //調用不可訪問或不存在的靜態(tài)方法時被調用
  public static function __callStatic($name, $arguments)
  {
    echo $name . &#39;-&#39; . implode(&#39;,&#39;, $arguments);
    echo &#39;__callStatic called&#39;.PHP_EOL;
  }
 
  //對不可訪問或不存在的屬性調用isset()或empty()時被調用
  public function __isset($name)
  {
    echo $name;
    echo &#39;__isset called&#39;.PHP_EOL;
    return true;
  }
 
  //對不可訪問或不存在的屬性進行unset時被調用
  public function __unset($name)
  {
    echo $name;
    echo &#39;__unset called&#39;.PHP_EOL;
  }
 
  //serialize時被調用，當你不需要保存大對象的所有數據時很有用
  public function __sleep()
  {
    echo &#39;__sleep called&#39;.PHP_EOL;
    return array(&#39;var1111111111&#39;);
  }
 
  //unserialize時被調用，可用于做些對象的初始化操作
  public function __wakeup()
  {
    echo &#39;__wakeup called&#39;.PHP_EOL;
    $this->var = &#39;test after wakeup&#39;;
  }
 
  //當一個類被轉換成字符串時被調用
  public function __toString()
  {
    return &#39;__toString called&#39;.PHP_EOL;
  }
 
  //進行對象clone時被調用，用來調整對象的克隆行為
  public function __clone()
  {
    echo &#39;__clone called&#39;.PHP_EOL;
  }
 
  //當以函數方式調用對象時被調用
  public function __invoke()
  {
    echo &#39;__invoke called&#39;.PHP_EOL;
  }
 
  //當調用var_export()導出類時，此靜態(tài)方法被調用。用__set_state的返回值做為var_export的返回值。
  public static function __set_state($arr)
  {
    return &#39;__set_state called&#39;.PHP_EOL;
  }
 
  //當調用var_dump()打印對象時被調用（當你不想打印所有屬性）適用于PHP5.6版本
  public function __debuginfo($arr)
  {
    echo &#39;__debuginfo called&#39;.PHP_EOL;
    return array(
      &#39;var&#39; => &#39;test fro __debuginfo&#39;
    );
  }
}
 
$m = new Magic(); //__construct()被調用
$m->not_exist_property = test; //__set()被調用
echo $m->not_exist_property;//__get()被調用
$m->abc(1,2,3); //__call()被調用
echo isset($m->not_exist_property); //__isset()被調用，返回bool值
unset($m->not_exist_property); //__unset()被調用
echo $tmp = serialize($m); //__sleep()被調用
unserialize($tmp); //__wakeup()被調用
$m1 = clone $m; //__clone()被調用，對象默認是引用傳遞，使用clone關鍵詞則可實現(xiàn)對象復制
$m(); //__invoke()
eval( &#39;$m2 = &#39; . var_export ( $m , true ) . &#39;;&#39; );var_dump($m2);
var_dump($m);
//最后__destruct()被調用
 
/*
結果：
__construct called
not_exist_property-test__set called
not_exist_property__get called
abc-1,2,3__call called
not_exist_property__isset called
1not_exist_property__unset called
__sleep called
O:5:"Magic":1:{s:13:"var1111111111";N;}__wakeup called
__destruct called
__clone called
__invoke called
string(20) "__set_state called
"
class Magic#1 (1) {
 public $var =>
 string(4) "test"
}
__destruct called
__destruct called
 
 
*/

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